Discovery of the gut microbial signature driving the efficacy of prebiotic intervention in obese patients

Captopril Alleviates Chondrocyte Senescence in DOCA-Salt Hypertensive Rats Associated with Gut Microbiome Alteration

Gut microbiota is the key controller of healthy aging. Hypertension and osteoarthritis (OA) are two frequently co-existing age-related pathologies in older adults. Both are associated with gut microbiota dysbiosis. Hereby, we explore gut microbiome alteration in the Deoxycorticosterone acetate (DOCA)-induced hypertensive rat model. Captopril, an anti-hypertensive medicine, was chosen to attenuate joint damage. Knee joints were harvested for radiological and histological examination; meanwhile, fecal samples were collected for 16S rRNA and shotgun sequencing. The 16S rRNA data was annotated using Qiime 2 v2019.10, while metagenomic data was functionally profiled with HUMAnN 2.0 database. Differential abundance analyses were adopted to identify the significant bacterial genera and pathways from the gut microbiota. DOCA-induced hypertension induced p16INK4a+ senescent cells (SnCs) accumulation not only in the aorta and kidney (p < 0.05) but also knee joint, which contributed to articular cartilage degradation and subchondral bone disturbance. Captopril removed the p16INK4a + SnCs from different organs, partially lowered blood pressure, and mitigated cartilage damage. Meanwhile, these alterations were found to associate with the reduction of Escherichia-Shigella levels in the gut microbiome. As such, gut microbiota dysbiosis might emerge as a metabolic link in chondrocyte senescence induced by DOCA-triggered hypertension. The underlying molecular mechanism warrants further investigation.

Sex Difference is a Determinant of Gut Microbes and Their Metabolites SCFAs/MCFAs in High Fat Diet Fed Rats

There are gender differences in obesity and related metabolic diseases, but the mechanism of these differences has not been elucidated. Gut microbiota has been recently recognized as a pivotal determinant of obesity and related diseases. The aim of the present study was to investigate sex differences in gut microbiota and its metabolites in an obesity rat model induced by prolonged high-fat-diet (HFD) feeding. In this study, male and female Sprague-Dawley rats were fed normal chow or HFD for 16 weeks (n = 8 for each group). We found that comparing with male rats on HFD (MHFD), female rats on HFD (FHFD) gained more body weight percentage, while had lower body weight gain efficiency and less severity of hepatic steatosis. HFD induced decreased taxon diversity and richness of gut microbiota, and FHFD group had even lower diversity than MHFD group. Among key genera, HFD induced increased Bilophila in male rats but not in female rats. Compared with the MHFD group, FHFD group possessed increases of Akkermansia and Murimonas, and decreases of Acetanaerobacterium, Bacteroides, Bilophila, Blautia and Romboutsia. The levels of total SCFAs in colon contents were increased in tendency in HFD-fed rats of both sexes. FHFD group had increased propionate and decreased ratio of acetate to propionate and butyrate than MHFD group. For MCFAs, HFD induced increases in undecanoic acid and lauric acid in female rats but not in males. In conclusion, HFD induced sex-related alterations in gut microbiome and short/medium-chain fatty acids in rats.

Inulin accelerates weight loss in obese mice by regulating gut microbiota and serum metabolites

Several studies indicated that the gut microbiota might participate in the beneficial effect of inulin on obesity. However, the mechanisms involved were still largely unknown. Sixteen high-fat diets (HFDs)-induced obese C57BL/6 mice were converted to a normal diet and then randomized into two groups, OND (obese mice + normal diet) group gavage-fed for 10 weeks with normal saline and ONDI (obese mice + normal diet + inulin) group with inulin at 10 g/kg/day. The body weight of HFD-induced obese mice showed different degrees of decrease in both groups. However, the ONDI group lost more weight and returned to normal earlier. Compared to the OND group, inulin supplementation significantly shifted the composition and structure of gut microbiota, such as higher α diversity. The β diversity analysis also confirmed the changes in gut microbiota composition between groups. At the genus level, the abundance of Alistipes was considerably increased, and it was significantly correlated with inulin supplementation (r = 0.72, P = 0.002). Serum metabolite levels were distinctly altered after inulin supplementation, and 143 metabolites were significantly altered in the ONDI group. Among them, indole-3-acrylic acid level increased more than 500-fold compared to the OND group. It was also strongly positive correlation with Alistipes (r = 0.72, P = 0.002) and inulin supplementation (r = 0.99, P = 9.2e−13) and negatively correlated with obesity (r = −0.72, P = 0.002). In conclusion, inulin supplementation could accelerate body weight loss in obese mice by increasing Alistipes and indole-3-acrylic acid level.

Assessment of the safety and probiotic properties of Roseburia intestinalis: A potential “Next Generation Probiotic”

Roseburia intestinalis is an anaerobic bacterium that produces butyric acid and belongs to the phylum Firmicutes. There is increasing evidence that this bacterium has positive effects on several diseases, including inflammatory bowel disease, atherosclerosis, alcoholic fatty liver, colorectal cancer, and metabolic syndrome, making it a potential “Next Generation Probiotic.” We investigated the genomic characteristics, probiotic properties, cytotoxicity, oral toxicity, colonization characteristics of the bacterium, and its effect on the gut microbiota. The genome contains few genes encoding virulence factors, three clustered regularly interspaced short palindromic repeat (CRISPR) sequences, two Cas genes, no toxic biogenic amine synthesis genes, and several essential amino acid and vitamin synthesis genes. Seven prophages and 41 genomic islands were predicted. In addition to a bacteriocin (Zoocin A), the bacterium encodes four metabolic gene clusters that synthesize short-chain fatty acids and 222 carbohydrate-active enzyme modules. This bacterium is sensitive to antibiotics specified by the European Food Safety Authority, does not exhibit hemolytic or gelatinase activity, and exhibits some acid resistance. R. intestinalis adheres to intestinal epithelial cells and inhibits the invasion of certain pathogens. In vitro experiments showed that the bacterium was not cytotoxic. R. intestinalis did not affect the diversity or abundance of the gut flora. Using the fluorescent labelling method, we discovered that R. intestinalis colonizes the cecum and mucus of the colon. An oral toxicity study did not reveal any obvious adverse effects. The lethal dose (LD)50 of R. intestinalis exceeded 1.9 × 10⁹ colony forming units (CFU)/kg, whereas the no observed adverse effect level (NOAEL) derived from this study was 1.32 × 10⁹ CFU/kg/day for 28 days. The current research shows that, R. intestinalis is a suitable next-generation probiotic considering its probiotic properties and safety.

Ruminal Microbiota Determines the High-Fiber Utilization of Ruminants: Evidence from the Ruminal Microbiota Transplant

The rumen, which contains a series of prokaryotes and eukaryotes with high abundance, determines the high ability to degrade complex carbohydrates in ruminants. Using 16S rRNA gene sequencing, we compared the ruminal microbiota of dairy goats with that in the foregut and colon of mice and found more Bacteroides identified in the rumen, which helps ruminants to utilize plant-derived polysaccharides, cellulose, and other structural carbohydrates. Furthermore, high-fiber diets did not significantly increase intestinal fiber-degrading bacteria in mice, but did produce higher levels of ruminal fiber-degrading bacteria in dairy goats. Through rumen microbe transplantation (RMT), we found that rumen-derived fiber-degrading bacteria can colonize the intestines of mice to exert their fiber-degrading function, but their colonization efficiency is affected by diet. Additionally, the colonization of these fiber-degrading bacteria in the colon may involve higher content of butyrate in the colon, protecting the colonic epithelial barrier and promoting energy metabolism. Overall, the fiber degradation function of rumen bacteria through RMT was verified, and our results provide new insights into isolating the functional and beneficial fiber-degrading bacteria in the rumen, providing a theoretical basis for the role of dietary fiber in intestinal health. IMPORTANCE Ruminants have a powerful progastric digestive system that converts structural carbohydrates into nutrients useful to humans. It is well known that this phenomenon is due to the fact that the rumen of ruminants is a natural microbial fermenter, which can ferment structural carbohydrates such as cellulose and hemicellulose and transform them into volatile fatty acids to supply energy for host. However, monogastric animals have an inherent disadvantage in utilizing fiber, so screening rumen-derived fiber-degrading bacteria as a fermentation strain for biological feed is needed in an attempt at improving the fiber digestibility of monogastric animals. In this study, a ruminal microbiota transplant experiment from goats to mice proves that ruminal microbiota could serve as a key factor in utilization of high-fiber diets and provides a new perspective for the development of probiotics with fiber degradation function from the rumen and the importance of the use of prebiotics during the intake of probiotics.

Targeting the Gut Microbiome to Treat Metabolic Dysfunction-Associated Fatty Liver Disease: Ready for Prime Time?

Numerous studies show a modification of the gut microbiota in patients with obesity or diabetes. Animal studies have also shown a causal role of gut microbiota in liver metabolic disorders including steatosis whereas the human situation is less clear. Patients with metabolic dysfunction associated fatty liver disease (MAFLD) also have a modification in their gut microbiota composition but the changes are not fully characterized. The absence of consensus on a precise signature is probably due to disease heterogeneity, possible concomitant medications and different selection or evaluation criteria. The most consistent changes were increased relative abundance of Proteobacteria, Enterobacteriaceae and Escherichia species and decreased abundance of Coprococcus and Eubacterium. Possible mechanisms linking the microbiota and MAFLD are increased intestinal permeability with translocation of microbial products into the portal circulation, but also changes in the bile acids and production of microbial metabolites such as ethanol, short chain fatty acids and amino acid derivatives able to modulate liver metabolism and inflammation. Several interventional studies exist that attempt to modulate liver disease by administering antibiotics, probiotics, prebiotics, synbiotics, postbiotics or fecal transplantation. In conclusion, there are both gaps and hopes concerning the interest of gut microbiome evaluation for diagnosis purposes of MAFLD and for new therapeutic developments that are often tested on small size cohorts.

Ecological dynamics of the gut microbiome in response to dietary fiber

Dietary fibers are generally thought to benefit intestinal health. Their impacts on the composition and metabolic function of the gut microbiome, however, vary greatly across individuals. Previous research showed that each individual's response to fibers depends on their baseline gut microbiome, but the ecology driving microbiota remodeling during fiber intake remained unclear. Here, we studied the long-term dynamics of the gut microbiome and short-chain fatty acids (SCFAs) in isogenic mice with distinct microbiota baselines fed with the fermentable fiber inulin and resistant starch compared to the non-fermentable fiber cellulose. We found that inulin produced a generally rapid response followed by gradual stabilization to new equilibria, and those dynamics were baseline-dependent. We parameterized an ecology model from the time-series data, which revealed a group of bacteria whose growth significantly increased in response to inulin and whose baseline abundance and interspecies competition explained the baseline dependence of microbiome density and community composition dynamics. Fecal levels of SCFAs, such as propionate, were associated with the abundance of inulin responders, yet inter-individual variation of gut microbiome impeded the prediction of SCFAs by machine learning models. We showed that our methods and major findings were generalizable to dietary resistant starch. Finally, we analyzed time-series data of synthetic and natural human gut microbiome in response to dietary fiber and validated the inferred interspecies interactions in vitro. This study emphasizes the importance of ecological modeling to understand microbiome responses to dietary changes and the need for personalized interventions.

Dietary Component-Induced Inflammation and Its Amelioration by Prebiotics, Probiotics, and Synbiotics

A balanced diet with many dietary components maintains immune homeostasis directly by interacting with innate and adaptive immune components or indirectly through gut microbiota and their metabolites. Dietary components may inhibit pro-inflammatory mediators and promote anti-inflammatory functions or vice versa. Western diets with imbalanced dietary components skew the immune balance toward pro-inflammation and induce intestinal inflammation, consequently leading to many intestinal and systemic inflammatory diseases like ulcerative colitis, Crohn's disease, irritable bowel syndrome, cardiovascular problems, obesity, and diabetes. The dietary component-induced inflammation is usually chronic in nature and frequently caused or accompanied by alterations in gut microbiota. Therefore, microbiome-targeted therapies such as probiotics, prebiotics and synbiotics hold great potentials to amend immune dysregulation and gut dysbiosis, preventing and treating intestinal and systemic inflammatory diseases. Probiotics, prebiotics and synbioitcs are progressively being added to foods and beverages, with claims of health benefits. However, the underlining mechanisms of these interventions for preventing and treating dietary component-induced inflammation are still not very clear. In addition, possibly ineffective or negative consequences of some probiotics, prebiotics and synbiotics call for stringent testing and regulation. Here, we will first briefly review inflammation, in terms of its types and the relationship between different dietary components and immune responses. Then, we focus on current knowledge about the direct and indirect effects of probiotics, prebiotics and synbiotics on intestinal and systemic inflammation. Understanding how probiotics, prebiotics and synbiotics modulate the immune system and gut microbiota will improve our strategies for preventing and treating dietary component-induced intestinal inflammation and inflammatory diseases.

Akkermansia muciniphila and Gut Immune System: A Good Friendship That Attenuates Inflammatory Bowel Disease, Obesity, and Diabetes

Akkermansia muciniphila is a Gram-negative anaerobic mucus-layer-degrading bacterium that colonizes the intestinal mucosa of humans and rodents. Metagenomic data have shown an inverse correlation between the abundance of A. muciniphila and diseases such as inflammatory bowel disease (IBD), obesity, and diabetes. Thus, in recent decades, the potential of this bacterium as an immunomodulatory probiotic for autoimmune and chronic inflammatory diseases has been explored in experimental models. Corroborating these human correlation data, it has been reported that A. muciniphila slows down the development and progression of diabetes, obesity, and IBD in mice. Consequently, clinical studies with obese and diabetic patients are being performed, and the preliminary results are very promising. Therefore, this mini review highlights the main findings regarding the beneficial roles of A. muciniphila and its action mechanisms in autoimmune and chronic inflammatory diseases.

Perspective: Leveraging the Gut Microbiota to Predict Personalized Responses to Dietary, Prebiotic, and Probiotic Interventions

Humans often show variable responses to dietary, prebiotic, and probiotic interventions. Emerging evidence indicates that the gut microbiota is a key determinant for this population heterogeneity. Here, we provide an overview of some of the major computational and experimental tools being applied to critical questions of microbiota-mediated personalized nutrition and health. First, we discuss the latest advances in in silico modeling of the microbiota-nutrition-health axis, including the application of statistical, mechanistic, and hybrid artificial intelligence models. Second, we address high-throughput in vitro techniques for assessing interindividual heterogeneity, from ex vivo batch culturing of stool and continuous culturing in anaerobic bioreactors, to more sophisticated organ-on-a-chip models that integrate both host and microbial compartments. Third, we explore in vivo approaches for better understanding of personalized, microbiota-mediated responses to diet, prebiotics, and probiotics, from nonhuman animal models and human observational studies, to human feeding trials and crossover interventions. We highlight examples of existing, consumer-facing precision nutrition platforms that are currently leveraging the gut microbiota. Furthermore, we discuss how the integration of a broader set of the tools and techniques described in this piece can generate the data necessary to support a greater diversity of precision nutrition strategies. Finally, we present a vision of a precision nutrition and healthcare future, which leverages the gut microbiota to design effective, individual-specific interventions.

Ectopic Colonization and Immune Landscapes of Periodontitis Microbiota in Germ-Free Mice With Streptozotocin-Induced Type 1 Diabetes Mellitus

A two-way relationship between diabetes and periodontitis has been discussed recently. Periodontitis microbiota might affect the immune homeostasis of diabetes, but the molecular mechanism of their interactions is still not clear. The aims of this study were to clarify the possible immune regulatory effects of periodontitis microbiota on diabetes and the correlation between immunomodulation and ectopic colonization. A model of germ-free mice with streptozotocin-induced type 1 diabetes mellitus (T1D), which was orally inoculated with mixed saliva samples for 2 weeks, was used in this study. Those mice were randomly divided into two groups, namely, SP (where the T1D mice were orally inoculated with mixed saliva samples from periodontitis patients) and SH (where the T1D mice were orally inoculated with mixed saliva samples from healthy subjects). Ectopic colonization of saliva microbiota was assessed using culture-dependent method and Sanger sequencing, and the composition of gut microbiota was analyzed using 16S rRNA gene sequencing. Changes in 15 types of immune cells and six cytokines either from the small intestine or spleen were detected by multicolor flow cytometry. The correlation between gut microbiota and immune cells was evaluated by redundancy analysis. Although periodontitis microbiota minorly colonized the lungs, spleens, and blood system, they predominantly colonized the gut, which was mainly invaded by Klebsiella. SH and SP differed in beta diversity of the gut bacterial community. Compared to SH, microbial alteration in small intestine occurred with an increase of Lacticaseibacillus, Bacillus, Agathobacter, Bacteroides, and a decrease of Raoultella in SP. More types of immune cells were disordered in the spleen than in the small intestine by periodontitis microbiota, mainly with a dramatical increase in the proportion of macrophages, plasmacytoid dendritic cells (pDCs), monocytes, group 3 innate lymphoid cells, CD4-CD8- T cells and Th17 cells, as well as a decline of αβT cells in SP. Cytokines of IFNγ, IL17, and IL22 produced by CD4 + T cells as well as IL22 produced by ILCs of small intestine rose in numbers, and the intestinal and splenic pDCs were positively regulated by gut bacterial community in SP. In conclusion, periodontitis microbiota invasion leads to ectopic colonization of the extra-oral sites and immune cells infiltration, which might cause local or systemic inflammation. Those cells are considered to act as a “bridge” between T1D and periodontitis.

The efficacy of probiotics supplementation for the treatment of atopic dermatitis in adults: a systematic review and meta-analysis

BACKGROUND

There is a lack of certain evidence for the therapeutic efficacy of probiotics for adult atopic dermatitis (AD).

METHODS

PubMed, EMBASE, and the Cochrane Database were searched for relevant studies, and randomized controlled trials of AD describing treatment with single/mixed probiotic therapy were included. Changes in outcomes were calculated by standard mean difference (SMD) and 95% confidence interval (CI). Relative efficacies of the probiotics were ranked by the surface under the cumulative ranking (SUCRA).

RESULTS

Nine studies with a total of 402 participants, including 208 AD patients who received probiotic treatments and 194 controls, were considered during the current analysis. A reduction in disease severity for probiotic supplementation compared to controls in both the short term (SMD: 0.63; 95% CI: 0.02-1.25) and the long term (SMD: 1.57; 95% CI: 0.66-2.49). There was a significant improvement in long-term quality of life after probiotic supplementation compared with controls (SMD: 0.74; 95% CI: 0.39-1.09). A mixture of L. salivarius (LS01) and Bifidobacterium (BR03) was found the highest probability of the best supplementation.

CONCLUSIONS

Probiotic supplementation decreases clinical severity and improves the quality of life among adult AD patients. The mixture of LS01 and BR03 appeared optimal.

Anti-obesity effects of Laminaria japonica fucoidan in high-fat diet-fed mice vary with the gut microbiota structure

Previous studies have indicated that fucoidan could resist high-fat-diet (HFD)-induced obesity by modulating the composition of gut microbiota. However, the outcome of dietary intervention may differ between individuals due to large inter-individual variability in gut microbiota. Thus, the present study aimed to investigate the possible discrepancy of the anti-obesity effects of fucoidan supplementation in HFD-fed mice models with different gut microbiota communities. In the present study, the anti-obesity effects of fucoidan isolated from Laminaria japonica (FucLj) on normal mice and microbiota-altered mice treated with penicillin or metronidazole were compared and investigated. The 16S rRNA sequencing revealed the differences of gut microbiota among penicillin-treated, metronidazole-treated and normal groups, and mice treated with penicillin were characterized by greater relative abundance of the phylum Bacteroidetes and the families Muribaculaceae and Bacteroidaceae. Furthermore, FucLj ameliorated HFD-induced body weight gain, fat accumulation, serum lipid profiles, insulin resistance, hepatic steatosis and adipocyte hypertrophy in penicillin-treated and untreated mice, while no effects were observed in metronidazole-treated mice. Overall, mice with different initial gut microbiota responded differently to FucLj supplementation on a high-fat diet, and metronidazole-sensitive gut bacteria negatively correlated with obesity symptoms and were required for the anti-obesity effects of FucLj. Moreover, the anti-obesity effects were not dependent on the utilization of FucLj by gut microbiota to produce SCFAs. These findings indicate that evaluation of the gut microbiota structure before dietary interventions is helpful for enhancing the beneficial outcomes of dietary fiber supplementation and provide a rationale for the further application of dietary fucoidan in a personalized way.

Polydatin, A Glycoside of Resveratrol, Is Better Than Resveratrol in Alleviating Non-alcoholic Fatty Liver Disease in Mice Fed a High-Fructose Diet

Resveratrol (RES) is considered to be an activator of AMP-activated protein kinase (AMPK) with many reported health benefits. Polydatin (POD) is a natural precursor and glycosylated form of RES. The glycoside structure of POD alters the bioactivity. Overnutrition-stimulated reactive oxygen species (ROS) promote the AMPK suppression and metabolic dysregulation. The present work compared the effects of POD and RES in ameliorating energy homeostasis imbalance in mice fed a high-fructose diet and elucidated the underlying mechanisms of action. Our results showed that POD elevated the fecal levels of valeric acid and caproic acid via modification of gut microbiota, while RES did not significantly influence the levels of fecal short-chain fatty acids (SCFAs). Both POD and RES markedly decreased the oxidative stress and activated the AMPK signaling pathways in the liver. POD and RES exerted a similar effect in alleviating glucose dysmetabolism, but POD was more effective in ameliorating lipid dysmetabolism than RES. Furthermore, valeric acid and caproic acid alone can activate the AMPK and ameliorate hypercholesterolemia, and enhance the effects of POD on improving lipid metabolism in mice. Overall, for the first time, we demonstrated that POD administration elevated the fecal levels of valeric acid and caproic acid by modifying gut microbiota, thus promoting AMPK activation may be the underlying mechanism that POD is superior to RES in alleviating the lipid dysmetabolism. Our results suggest that POD may be an alternative for RES as an AMPK activator.

Dietary macronutrients and the gut microbiome: a precision nutrition approach to improve cardiometabolic health

Accumulating evidence indicates that the gut microbiome is an important regulator of body weight, glucose and lipid metabolism, and inflammatory processes, and may thereby play a key role in the aetiology of obesity, insulin resistance and type 2 diabetes. Interindividual responsiveness to specific dietary interventions may be partially determined by differences in baseline gut microbiota composition and functionality between individuals with distinct metabolic phenotypes. However, the relationship between an individual's diet, gut microbiome and host metabolic phenotype is multidirectional and complex, yielding a challenge for practical implementation of targeted dietary guidelines. In this review, we discuss the latest research describing interactions between dietary composition, the gut microbiome and host metabolism. Furthermore, we describe how this knowledge can be integrated to develop precision-based nutritional strategies to improve bodyweight control and metabolic health in humans. Specifically, we will address that (1) insight in the role of the baseline gut microbial and metabolic phenotype in dietary intervention response may provide leads for precision-based nutritional strategies; that (2) the balance between carbohydrate and protein fermentation by the gut microbiota, as well as the site of fermentation in the colon, seems important determinants of host metabolism; and that (3) 'big data', including multiple omics and advanced modelling, are of undeniable importance in predicting (non-)response to dietary interventions. Clearly, detailed metabolic and microbial phenotyping in humans is necessary to better understand the link between diet, the gut microbiome and host metabolism, which is required to develop targeted dietary strategies and guidelines for different subgroups of the population.

Experimental evaluation of ecological principles to understand and modulate the outcome of bacterial strain competition in gut microbiomes

It is unclear if coexistence theory can be applied to gut microbiomes to understand their characteristics and modulate their composition. Through experiments in gnotobiotic mice with complex microbiomes, we demonstrated that strains of Akkermansia muciniphila and Bacteroides vulgatus could only be established if microbiomes were devoid of these species. Strains of A. muciniphila showed strict competitive exclusion, while B. vulgatus strains coexisted but populations were still influenced by competitive interactions. These differences in competitive behavior were reflective of genomic variation within the two species, indicating considerable niche overlap for A. muciniphila strains and a broader niche space for B. vulgatus strains. Priority effects were detected for both species as strains’ competitive fitness increased when colonizing first, which resulted in stable persistence of the A. muciniphila strain colonizing first and competitive exclusion of the strain arriving second. Based on these observations, we devised a subtractive strategy for A. muciniphila using antibiotics and showed that a strain from an assembled community can be stably replaced by another strain. By demonstrating that competitive outcomes in gut ecosystems depend on niche differences and are historically contingent, our study provides novel information to explain the ecological characteristics of gut microbiomes and a basis for their modulation.

Diet Supplementation with NUTRIOSE, a Resistant Dextrin, Increases the Abundance of Parabacteroides distasonis in the Human Gut

SCOPE

An imbalance of the gut microbiota ("dysbiosis") is associated with numerous chronic diseases, and its modulation is a promising novel therapeutic approach. Dietary supplementation with soluble fiber is one of several proposed modulation strategies. This study aims at confirming the impact of the resistant dextrin NUTRIOSE (RD), a soluble fiber with demonstrated beneficial health effects, on the gut microbiota of healthy individuals.

METHODS AND RESULTS

Fifty healthy women are enrolled and supplemented daily with either RD (n = 24) or a control product (n = 26) during 6 weeks. Characterization of the fecal metagenome with shotgun sequencing reveals that RD intake dramatically increases the abundance of the commensal bacterium Parabacteroides distasonis. Furthermore, presence in metagenomes of accessory genes from P. distasonis, coding for susCD (a starch-binding membrane protein complex) is associated with a greater increase of the species. This suggests that response to RD might be strain-dependent.

CONCLUSION

Supplementation with RD can be used to specifically increase P. distasonis in gut microbiota of healthy women. The magnitude of the response may be associated with fiber-metabolizing capabilities of strains carried by subjects. Further research will seek to confirm that P. distasonis directly modulates the clinical effects observed in other studies.

Inulin fructans in diet: Role in gut homeostasis, immunity, health outcomes and potential therapeutics

Inulin consumption in both humans and animal models is recognized for its prebiotic action with the most consistent change that lies in enhancing the growth and functionality of Bifidobacterium bacteria, as well as its effect on host gene expression and metabolism. Further, inulin-type fructans are utilized in the colon by bacterial fermentation to yield short-chain fatty acids (SCFAs), which play important role in its biological effects both locally inside the gut and in systemic actions. The gut symbiosis sustained by inulin supplementation among other dietary fibers exerts preventive and/or therapeutic options for many metabolic disorders including obesity, type 2 diabetes mellitus, cardiometabolic diseases, kidney diseases and hyperuricemia. Although, gastrointestinal negative effects due to inulin consumption were reported, such as gastrointestinal symptoms in humans and exacerbated inflammatory bowel disease (IBD) in mice. This comprehensive review aims to present the whole story of how inulin functions as a prebiotic at cellular levels and the interplay between physiological, functional and immunological responses inside the animal or human gut as influenced by inulin in diets, in context to its structural composition. Such review is of importance to identify management and feed strategies to optimize gut health, for instance, consumption of the tolerated doses to healthy adults of 10 g/day of native inulin or 5 g/day of naturally inulin-rich chicory extract. In addition, inulin-drug interactions should be further clarified particularly if used as a supplement for the treatment of degenerative diseases (e.g., diabetes) over a long period. The combined effect of probiotics and inulin appears more effective, and more research on this synergy is still needed.

Overall Structural Alteration of Gut Microbiota and Relationships with Risk Factors in Patients with Metabolic Syndrome Treated with Inulin Alone and with Other Agents: An Open-Label Pilot Study

Objective

The relative contribution of some products with prebiotic effects, such as inulin, together with medications specific to the human gut microbiome has not been comprehensively studied. The present study determined the potential for manipulating populations in the gut microbiome using inulin alone and combined with other agents in individuals with metabolic syndrome (MetS). The study also assessed whether there is relationship variability in multiple clinical parameters in response to intervention with the changes in the gut milieu. Participants/Methods. This single-centre, single-blinded, randomised community-based pilot trial randomly assigned 60 patients (mean age, 46.3 y and male, 43%) with MetS to receive either inulin, inulin+traditional Chinese medicine (TCM), or inulin+metformin for 6 months. Lipid profiles, blood glucose, and uric acid (UA) levels were analysed in venous blood samples collected after overnight fast of 8 h at baseline and at the end of the follow-up period. Microbiota from stool samples were taxonomically analysed using 16S RNA amplicon sequencing, and an integrative analysis was conducted on microbiome and responsiveness data at 6 months.

Results

The results of 16S rRNA sequencing showed that inulin resulted in a higher proportion of Bacteroides at the endpoint compared with inulin+TCM and inulin+metformin (p = 0.024). More Romboutsia (p = 0.043), Streptococcus (p < 0.001), and Holdemanella (p = 0.011) were found in inulin+TCM and inulin+metformin samples. We further identified gut microbiota relationships with lipids, UA, and glucose that impact the development of MetS.

Conclusion

Among the groups, inulin alone or combined with metformin or TCM altered specific gut microbiota taxa but not the general diversity. Accordingly, we analysed metabolites associated with microbiota that might provide more information about intrinsic differences. Consequently, a reliable method could be developed for treating metabolic syndrome in the future.

Prebiotics and the Human Gut Microbiota: From Breakdown Mechanisms to the Impact on Metabolic Health

The colon harbours a dynamic and complex community of microorganisms, collectively known as the gut microbiota, which constitutes the densest microbial ecosystem in the human body. These commensal gut microbes play a key role in human health and diseases, revealing the strong potential of fine-tuning the gut microbiota to confer health benefits. In this context, dietary strategies targeting gut microbes to modulate the composition and metabolic function of microbial communities are of increasing interest. One such dietary strategy is the use of prebiotics, which are defined as substrates that are selectively utilised by host microorganisms to confer a health benefit. A better understanding of the metabolic pathways involved in the breakdown of prebiotics is essential to improve these nutritional strategies. In this review, we will present the concept of prebiotics, and focus on the main sources and nature of these components, which are mainly non-digestible polysaccharides. We will review the breakdown mechanisms of complex carbohydrates by the intestinal microbiota and present short-chain fatty acids (SCFAs) as key molecules mediating the dialogue between the intestinal microbiota and the host. Finally, we will review human studies exploring the potential of prebiotics in metabolic diseases, revealing the personalised responses to prebiotic ingestion. In conclusion, we hope that this review will be of interest to identify mechanistic factors for the optimization of prebiotic-based strategies.

The human gut microbiota contributes to type-2 diabetes non-resolution 5-years after Roux-en-Y gastric bypass

Roux-en-Y gastric bypass (RYGB) is efficient at inducing drastic albeit variable weight loss and type-2 diabetes (T2D) improvements in patients with severe obesity and T2D. We hypothesized a causal implication of the gut microbiota (GM) in these metabolic benefits, as RYGB is known to deeply impact its composition. In a cohort of 100 patients with baseline T2D who underwent RYGB and were followed for 5-years, we used a hierarchical clustering approach to stratify subjects based on the severity of their T2D (Severe vs Mild) throughout the follow-up. We identified via nanopore-based GM sequencing that the more severe cases of unresolved T2D were associated with a major increase of the class Bacteroidia, including 12 species comprising Phocaeicola dorei, Bacteroides fragilis, and Bacteroides caecimuris. A key observation is that patients who underwent major metabolic improvements do not harbor this enrichment in Bacteroidia, as those who presented mild cases of T2D at all times. In a separate group of 36 patients with similar baseline clinical characteristics and preoperative GM sequencing, we showed that this increase in Bacteroidia was already present at baseline in the most severe cases of T2D. To explore the causal relationship linking this enrichment in Bacteroidia and metabolic alterations, we selected 13 patients across T2D severity clusters at 5-years and performed fecal matter transplants in mice. Our results show that 14 weeks after the transplantations, mice colonized with the GM of Severe donors have impaired glucose tolerance and insulin sensitivity as compared to Mild-recipients, all in the absence of any difference in body weight and composition. GM sequencing of the recipient animals revealed that the hallmark T2D-severity associated bacterial features were transferred and were associated with the animals' metabolic alterations. Therefore, our results further establish the GM as a key contributor to long-term glucose metabolism improvements (or lack thereof) after RYGB.

Targeting Gut Microbiota With Natural Polysaccharides: Effective Interventions Against High-Fat Diet-Induced Metabolic Diseases

Unhealthy diet, in particular high-fat diet (HFD) intake, can cause the development of several metabolic disorders, including obesity, hyperlipidemia, type 2 diabetes mellitus (T2DM), non-alcoholic fatty liver disease (NAFLD), and metabolic syndrome (MetS). These popular metabolic diseases reduce the quality of life, and induce premature death worldwide. Evidence is accumulating that the gut microbiota is inextricably associated with HFD-induced metabolic disorders, and dietary intervention of gut microbiota is an effective therapeutic strategy for these metabolic dysfunctions. Polysaccharides are polymeric carbohydrate macromolecules and sources of fermentable dietary fiber that exhibit biological activities in the prevention and treatment of HFD-induced metabolic diseases. Of note, natural polysaccharides are among the most potent modulators of the gut microbiota composition. However, the prebiotics-like effects of polysaccharides in treating HFD-induced metabolic diseases remain elusive. In this review, we introduce the critical role of gut microbiota human health and HFD-induced metabolic disorders. Importantly, we review current knowledge about the role of natural polysaccharides in improving HFD-induced metabolic diseases by regulating gut microbiota.

Physical activity enhances the improvement of body mass index and metabolism by inulin: a multicenter randomized placebo-controlled trial performed in obese individuals

BACKGROUND

Dietary interventions targeting the gut microbiota have been proposed as innovative strategies to improve obesity-associated metabolic disorders. Increasing physical activity (PA) is considered as a key behavioral change for improving health. We have tested the hypothesis that changing the PA status during a nutritional intervention based on prebiotic supplementation can alter or even change the metabolic response to the prebiotic. We confirm in obese subjects and in high-fat diet fed mice that performing PA in parallel to a prebiotic supplementation is necessary to observe metabolic improvements upon inulin.

METHODS

A randomized, single-blinded, multicentric, placebo-controlled trial was conducted in obese participants who received 16 g/day native inulin versus maltodextrin, coupled to dietary advice to consume inulin-rich versus -poor vegetables for 3 months, respectively, in addition to dietary caloric restriction. Primary outcomes concern the changes on the gut microbiota composition, and secondary outcomes are related to the measures of anthropometric and metabolic parameters, as well as the evaluation of PA. Among the 106 patients who completed the study, 61 patients filled a questionnaire for PA before and after intervention (placebo: n = 31, prebiotic: n = 30). Except the dietitian (who provided dietary advices and recipes book), all participants and research staff were blinded to the treatments and no advices related to PA were given to participants in order to change their habits. In parallel, a preclinical study was designed combining both inulin supplementation and voluntary exercise in a model of diet-induced obesity in mice.

RESULTS

Obese subjects who increased PA during a 3 months intervention with inulin-enriched diet exhibited several clinical improvements such as reduced BMI (- 1.6 kg/m²), decreased liver enzymes and plasma cholesterol, and improved glucose tolerance. Interestingly, the regulations of Bifidobacterium, Dialister, and Catenibacterium genera by inulin were only significant when participants exercised more. In obese mice, we highlighted a greater gut fermentation of inulin and improved glucose homeostasis when PA is combined with prebiotics.

CONCLUSION

We conclude that PA level is an important determinant of the success of a dietary intervention targeting the gut microbiota.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03852069 (February 22, 2019 retrospectively registered).

Curcumin Alleviates DSS-Induced Anxiety-Like Behaviors via the Microbial-Brain-Gut Axis

The anxiety and depression caused by inflammatory bowel diseases (IBD) are known to greatly affect the mental health of patients. The mechanism of psychiatric disorders caused by IBD is not fully understood. Previous research has suggested that the gut microbiome plays a key role in IBD. Curcumin is a yellow polyphenol extracted from the rhizome of the ginger plant, which has been shown to have effects against both depression and anxiety. Research has indicated that curcumin affects the gut microbiome and exerts antianxiety and neuroprotective effects through the microbiota-gut-brain axis (MGB). However, whether curcumin can alleviate the psychiatric disorders caused by IBD and how curcumin affects the MGB axis through the gut microbiota have not been fully understood. Therefore, this study was aimed at determining the metabolic parameters and microbiological environment in the peripheral and central nervous system to determine the effects of curcumin against anxiety induced by dextran sulfate sodium salt (DSS) in mice. To elaborate on the link between the gut microbiota and how curcumin alleviates anxiety-like behaviors, we performed a fecal microbiota transplantation (FMT) experiment. The results suggested that curcumin can effectively relieve anxiety-like behaviors caused by DSS in mice. Further, curcumin treatment can alleviate disturbances in the gut microbiota and systemic disorders of lipid metabolism caused by DSS. Finally, through FMT, we verified that curcumin increased phosphatidylcholine in the prefrontal cortex of the mice and alleviated DSS-induced anxiety-like behaviors by modulating specific gut microbiota. We also revealed that Muribaculaceae may be a key part of the gut microbiota for curcumin to alleviate DSS-induced anxiety-like behaviors through the MGB axis.

Gut microbiota and short chain fatty acids partially mediate the beneficial effects of inulin on metabolic disorders in obese ob/ob mice

Mounting evidence has linked both obesity and metabolic disorders with dysbiosis of the gut microbiota. Dietary inulin is conducive to modulating this dysbiosis, and represents a potential means to improve disorders of glucose and lipid metabolism. However, the mechanisms underlying these improvements are largely unclear. Obese ob/ob mice were fed a standard chow, a low fiber diet (LFD) or a high fiber diet (HFD) for 4 weeks, and the body weight, fecal short chain fatty acids (SCFAs) level, and plasma and liver lipid profiles were analyzed. Oral glucose tolerance testing, and gut microbiota sequencing were also conducted. Dietary inulin improved the dysbiosis of the gut microbiota, attenuated the decrease in phylum Bacteroidetes, repressed the increase of phylum Firmicutes, and led to an increase in the ratio of Firmicutes/Bacteroidetes. At the family level, inulin promoted the expansion of SCFAs-producing Ruminococcaceae and Lachnospiraceae bacteria, which increased the fecal SCFAs concentrations. At the genus level, inulin increased the levels of Bacteroides and Bifidobacteria. Furthermore, our results revealed that there was enhanced expression of angiopoietin-like protein 4 (ANGPTL4), which might be induced by the higher production of SCFAs, and this may underlie the improvements in the disorders of glucose and lipid metabolism seen in mice with added dietary inulin. In conclusion, inulin may ameliorate metabolic disorders by remodeling the gut microbiota and increasing the production of SCFAs, which might be mediated by the ANGPTL4-related signaling pathway. Interventions targeting the gut microbiota warrant further investigation as a novel therapy for metabolic diseases. PRACTICAL APPLICATIONS: Mounting evidence has linked both obesity and metabolic disorders with dysbiosis of the gut microbiota. Dietary inulin is conducive to modulating this dysbiosis, and represents a potential means to improve disorders of glucose and lipid metabolism. However, the mechanisms underlying these improvements are largely unclear. In the present study, we investigated the effects of dietary fiber (inulin) on metabolic homeostasis using ob/ob mice. The results of our study demonstrate that inulin-induced remodeling of the gut microbiota resulted in increased production of short chain fatty acids (SCFAs), leading to the enhanced expression of angiopoietin-like protein 4 (ANGPTL4), which improved the glucose and lipid metabolism. Our results suggest that the gut microbiota, SCFAs and ANGPTL4 pathway at least partially mediate the beneficial effects of inulin on metabolic disorders in ob/ob mice.

Gut microbiota-derived short-chain fatty acids and colorectal cancer: Ready for clinical translation?

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related death worldwide. It involves the complex interactions between genetic factors, environmental exposure, and gut microbiota. Specific changes in the gut microbiome and metabolome have been described in CRC, supporting the critical role of gut microbiota dysbiosis and microbiota-related metabolites in the tumorigenesis process. Short-chain fatty acids (SCFAs), the principal metabolites generated from the gut microbial fermentation of insoluble dietary fiber, can directly activate G-protein-coupled receptors (GPCRs), inhibit histone deacetylases (HDACs), and serve as energy substrates to connect dietary patterns and gut microbiota, thereby improving the intestinal health. A significantly lower abundance of SCFAs and SCFA-producing bacteria has been demonstrated in CRC, and the supplementation of SCFA-producing probiotics can inhibit intestinal tumor development. SCFAs-guided modulation in both mouse and human CRC models augmented their responses to chemotherapy and immunotherapy. This review briefly summarizes the complex crosstalk between SCFAs and CRC, which might inspire new approaches for the diagnosis, treatment and prevention of CRC on the basis of gut microbiota-derived metabolites SCFAs.

Akkermansia muciniphila: is it the Holy Grail for ameliorating metabolic diseases?

The increasing prevalence of metabolic diseases has become a severe public health problem. Gut microbiota play important roles in maintaining human health by modulating the host's metabolism. Recent evidences demonstrate that Akkermansia muciniphila is effective in improving metabolic disorders and is thus considered as a promising "next-generation beneficial microbe". In addition to the live A. muciniphila, similar or even stronger beneficial effects have been observed in pasteurized A. muciniphila and its components, including the outer membrane protein Amuc_1100, A. muciniphila-derived extracellular vesicles (AmEVs), and secreted protein P9. Hence, this paper presents a systemic review of recent progress in the effects and mechanisms of A. muciniphila and its components in the treatment of metabolic diseases, including obesity, type 2 diabetes mellitus, cardiovascular disease, and nonalcoholic fatty liver disease, as well as perspectives on its future study.

Integrated Analysis of the Cecal Microbiome and Plasma Metabolomics to Explore NaoMaiTong and Its Potential Role in Changing the Intestinal Flora and Their Metabolites in Ischemic Stroke

Ischemic stroke (IS), as a leading cause of disability worldwide, affects intestinal bacterial communities and their metabolites, while recent discoveries have highlighted the importance of the intestinal microflora in the development of IS. Systematic investigations of complex intestinal bacterial communities and their metabolites during ischemic brain injury contribute to elucidate the promising therapeutic targets for IS. However, the associations between intestinal microbiota and related circulating metabolic processes in IS remained unclear. Hence, to identify the changed microflora and their metabolites in IS of NaoMaiTong (NMT), an effective clinical medication, we established the middle cerebral artery occlusion/reperfusion (MCAO/R) model using conventionalized and pseudo-germ-free (PGF) rats. Subsequently, we systematically screen the microflora and related metabolites changing in IS via an integrated approach of cecal 16S rRNA sequencing combined with plasma metabolomics. We found that NMT relied on intestinal flora to improve stroke outcome in conventionalized rats while the protection of NMT was reduced in PGF rats. Total 35 differential bacterial genera and 26 differential microbial metabolites were regulated by NMT. Furthermore, L-asparagine and indoleacetaldehyde were significantly negatively correlated with Lachnospiraceae_UCG.001 and significantly positively correlated with Lachnoclostridium. Indoleacetaldehyde also presented a negative correlation with Lactobacillus and Bifidobacterium. 2-Hydroxybutyric acid was strongly negatively correlated with Ruminococcus, Lachnospiraceae_UCG.001 and Lachnospiraceae_UCG.006. Creatinine was strongly negatively correlated with Akkermansia. In summary, the research provided insights into the intricate interaction between intestinal microbiota and metabolism of NMT in IS. We identified above differential bacteria and differential endogenous metabolites which could be as prebiotic and probiotic substances that can influence prognosis in stroke and have potential to be used as novel therapeutic targets or exogenous drug supplements.

Anti-obesity natural products and gut microbiota

The link between gut microbiota and obesity or other metabolic syndromes is growing increasingly clear. Natural products are appreciated for their beneficial health effects in humans. Increasing investigations demonstrated that the anti-obesity bioactivities of many natural products are gut microbiota dependent. In this review, we summarized the current knowledge on anti-obesity natural products acting through gut microbiota according to their chemical structures and signaling metabolites. Manipulation of the gut microbiota by natural products may serve as a potential therapeutic strategy to prevent obesity.

Calebin-A prevents HFD-induced obesity in mice by promoting thermogenesis and modulating gut microbiota

Background and aim

Obesity is one of the complications of sedentary lifestyle and high-calorie food intake which become a global problem. Thermogenesis is a novel way to promote anti-obesity by consuming energy as heat rather than storing it as triacylglycerols. Over the last decade, growing evidence has identified the gut microbiota as a potential factor in the pathophysiology of obesity. Calebin A is a non-curcuminoid novel compound derived from the rhizome of medicinal turmeric with putative anti-obesity effects. However, its ability on promoting thermogenesis and modulating gut microbiota remain unclear.

Experimental procedure

C57BL/6J mice were fed either normal diet or high-fat diet (HFD) supplement with calebin A (0.1 and 0.5%) diet for 12 weeks. The composition of the gut microbiota was assessed by analyzing 16S rRNA gene sequences.

Results and conclusion

Mice treated with calebin A shows a remarkable alteration in microbiota composition compared with that of normal diet-fed or HFD-fed mice and is characterized by an enrichment of Akkermansia, Butyricicoccus, Ruminiclostridium_9, and unidentified_Ruminococcaceae. We also explored that calebin A reduce the weight and blood sugar of mice that are induced by HFD, and show a dose-dependent reaction. Moreover, calebin A decreases the weight of white, beige, and brown adipose tissue, and also restores liver weight. In cold exposure experiments, calebin A can better maintain rectal temperature through thermogenesis. In summary, calebin A has a good thermogenesis function and is effective in anti-obesity. It can be used as a novel gut microbiota modulator to prevent HFD-induced obesity.

Nutrition and Microbiome

The prevalence of overweight and obesity has reached epidemic proportions globally over the past few decades. The search for new management approaches continues and among them, targeting the gut microbiota can be envisioned. To date, numerous data showed the involvement of the gut microbes in the regulation and control of host metabolism. There are also increasing evidences highlighting the interactions between environmental factors, intrinsic factors, gut microbiota, and metabolic diseases. Diet emerges as the most relevant factor influencing the gut microbiome. Eating habits, as well as short-term consumption of specific diets, alter the gut microbiota composition. Moreover, nutritional disorders are associated with changes of the gut microbiota composition and/or function, as shown in obesity or type 2 diabetic patients versus healthy lean subjects. Targeting the gut microbiota for improving metabolic health appears as a new approach to manage obesity and cardio-metabolic risk. In this review, we have detailed the results of human interventions targeting the gut microbiome by prebiotic supplementation, prebiotics being defined as "substrates that are selectively utilized by the host microorganisms conferring a health benefit." If the potential benefit of this approach is obvious in preclinical models, the efficacy of prebiotics in humans is less reproducible. The inter-individual variability of response to dietary intervention can be dependent on the gut microbiota and we summarized the basal gut microbiota characteristics driving the metabolic response to dieting, prebiotic and dietary fiber intervention in the context of obesity and related metabolic diseases.

Microbiota and body weight control: Weight watchers within?

Background

Despite several decades of research, managing body weight remains an unsolved clinical problem. Health problems associated with dysregulated body weight, such as obesity and cachexia, exhibit several gut microbiota alterations. There is an increased interest in utilising the gut microbiota for body weight control, as it responds to intervention and plays an important role in energy extraction from food, as well as biotransformation of nutrients.

Scope of the review

This review provides an overview of the role of the gut microbiota in the physiological and metabolic alterations observed in two body weight dysregulation-related disorders, namely obesity and cachexia. Second, we assess the available evidence for different strategies, including caloric restriction, intermittent fasting, ketogenic diet, bariatric surgery, probiotics, prebiotics, synbiotics, high-fibre diet, and fermented foods – effects on body weight and gut microbiota composition. This approach was used to give insights into the possible link between body weight control and gut microbiota configuration.

Major conclusions

Despite extensive associations between body weight and gut microbiota composition, limited success could be achieved in the translation of microbiota-related interventions for body weight control in humans. Manipulation of the gut microbiota alone is insufficient to alter body weight and future research is needed with a combination of strategies to enhance the effects of lifestyle interventions.

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The gut microbiota is involved in the control of nutrient availability, appetite, and body weight.

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Both obesity and cachexia are associated with altered gut microbiota.

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Specific dietary and surgical approaches positively impact body weight and gut microbiota.

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Manipulation of the gut microbiota alone is insufficient to alter body weight in humans.

Therapeutic Potential of Butyrate for Treatment of Type 2 Diabetes

Metagenomics studies have shown that type 2 diabetes (T2D) is associated with an altered gut microbiota. Whereas different microbiota patterns have been observed in independent human cohorts, reduction of butyrate-producing bacteria has consistently been found in individuals with T2D, as well as in those with prediabetes. Butyrate is produced in the large intestine by microbial fermentations, particularly of dietary fiber, and serves as primary fuel for colonocytes. It also acts as histone deacetylase inhibitor and ligand to G-protein coupled receptors, affecting cellular signaling in target cells, such as enteroendocrine cells. Therefore, butyrate has become an attractive drug target for T2D, and treatment strategies have been devised to increase its intestinal levels, for example by supplementation of butyrate-producing bacteria and dietary fiber, or through fecal microbiota transplant (FMT). In this review, we provide an overview of current literature indicating that these strategies have yielded encouraging results and short-term benefits in humans, but long-term improvements of glycemic control have not been reported so far. Further studies are required to find effective approaches to restore butyrate-producing bacteria and butyrate levels in the human gut, and to investigate their impact on glucose regulation in T2D.

Gut microbiota response to sulfated sea cucumber polysaccharides in a differential manner using an in vitro fermentation model

Sea cucumber Stichopus japonicus has been consumed as high-valued seafood in Asian, and its sulfated polysaccharide (SCSPsj) has been inferred to benefit the host health via modulating gut microbiota composition. The present study compared the responses of gut microbiota communities from different donors to SCSPsj, and the key bacteria were identified by 16S rRNA gene sequencing analysis and in vitro fermentation with specific bacteria. Gut microbiota communities from 6 donors (A ~ F) utilized the polysaccharides to different degrees in vitro fermentation. Further comparison of Samples A and C demonstrated that Sample C with the relatively strong SCSPsj utilization capability possessed more Parabacteroides while Sample A contained more Bacteroides. Further in vitro fermentation of SCSPsj with 10 Parabacteroides and Bacteroides species suggests that Parabacteroides distasonis, enriched in Sample C, plays a critical role in the utilization of the polysaccharides. Moreover, short chain fatty acids and the metabolite profiles of Samples A and C were also compared, and the results showed that more beneficial metabolites were accumulated by the microbiota community consuming more sulfated sea cucumber polysaccharides. Our findings revealed that certain key members of gut microbiota, such as Parabacteroides distasonis, are critical for SCSPsj utilization in gut so as to influence the benefits of the polysaccharide supplement for host. Thus, to obtain better functional outcome for sulfated sea cucumber polysaccharides and sea cucumber, more attention needs to be paid to the effects of inter-individual differences in microbiota community structure.

Role of prebiotics in enhancing the function of next-generation probiotics in gut microbiota

With the development of high-throughput DNA sequencing and molecular analysis technologies, next-generation probiotics (NGPs) are increasingly gaining attention as live bacterial therapeutics for treatment of diseases. However, compared to traditional probiotics, NGPs are much more vulnerable to the harsh conditions in the human gastrointestinal tract, and their functional mechanisms in the gut are more complex. Prebiotics have been confirmed to play a critical role in improving the function and viability of traditional probiotics. Defined as substrates that are selectively utilized by host microorganisms conferring a health benefit, prebiotics are also important for NGPs. This review summarizes potential prebiotics for use with NGPs and clarifies their characteristics and functional mechanisms. Then we particularly focus on illustrating the protective effects of various prebiotics by enhancing the antioxidant capacity and their resistance to digestive fluids. We also elucidate the role of prebiotics in regulating anti-bacterial effects, intestinal barrier maintenance, and cross-feeding mechanisms of NPGs. With the expanding range of candidate NGPs and prebiotic substrates, more studies need to be conducted to comprehensively elucidate the interactions between prebiotics and NGPs outside and inside hosts, in order to boost their nutritional and healthcare applications.

Prebiotic inulin as a treatment of obesity related nonalcoholic fatty liver disease through gut microbiota: a critical review

The microbial-derived products, including short chain fatty acids, lipopolysaccharide and secondary bile acids, have been shown to participate in the regulation of hepatic lipid metabolism. Previous studies have demonstrated that prebiotics, such as oligosaccharide and inulin, have abilities to change the concentration of microbial-derived products through modulating the microbial community structure, thus controlling body weight and alleviating hepatic fat accumulation. However, recent evidence indicates that there are individual differences in host response upon inulin treatment due to the differences in host microbial composition before dietary intervention. Probably it is because of the multiple relationships among bacterial species (e.g., competition and mutualism), which play key roles in the degradation of inulin and the regulation of microbial structure. Thereby, analyzing the composition and function of initial gut microbiota is essential for improving the efficacy of prebiotics supplementation. Furthermore, considering that different structures of polysaccharides can be used by different microorganisms, the chemical structure of processed inulin should be tested before using prebiotic inulin to treat obesity related nonalcoholic fatty liver disease.

The Effects of Erchen Decoction on Gut Microbiota and Lipid Metabolism Disorders in Zucker Diabetic Fatty Rats

Obesity is a chronic metabolic disease caused by genetic and environmental factors that has become a serious global health problem. There is evidence that gut microbiota is closely related to the occurrence and development of obesity. Erchen Decoction (ECD), a traditional Chinese medicine, has been widely used for clinical treatment and basic research of obesity and related metabolic diseases in recent years. It can significantly improve insulin resistance (IR) and lipid metabolism disorders. However, there is no microbiological study on its metabolic regulation. In this study, we investigated the effects of ECD on obesity, especially lipid metabolism and the composition and function of gut microbiota in Zucker diabetic fatty (ZDF) rats, and explored the correlation between the biomarkers of gut microbiota and metabolite and host phenotype. The results showed that ECD could reduce body weight, improve IR and lipid metabolism, and reduce the concentration of free fatty acids (FFA) released from white adipose tissue (WAT) due to excessive lipolysis by interfering with the insulin receptor substrate 1 (IRS1)/protein kinase B (AKT)/protein kinase A (PKA)/hormone-sensitive triglyceride lipase (HSL) signaling pathway in ZDF rats. Additionally, ECD gradually adjusted the overall structure of changed gut microbiota, reversed the relative abundance of six genera, and changed the function of gut microbiota by reducing the content of propionic acid, a metabolite of gut microbiota, in ZDF rats. A potentially close relationship between biomarkers, especially Prevotella, Blautia, and Holdemania, propionic acid and host phenotypes were demonstrated through correlation analysis. The results suggested that the beneficial effects of ECD on obesity, especially lipid metabolism disorders, are related to the regulation of gut microbiota in ZDF rats. This provides a basis for further research on the mechanism and clinical application of ECD to improve obesity via gut microbiota.

From gut microbiota to host appetite: gut microbiota-derived metabolites as key regulators

Feelings of hunger and satiety are the key determinants for maintaining the life of humans and animals. Disturbed appetite control may disrupt the metabolic health of the host and cause various metabolic disorders. A variety of factors have been implicated in appetite control, including gut microbiota, which develop the intricate interactions to manipulate the metabolic requirements and hedonic feelings. Gut microbial metabolites and components act as appetite-related signaling molecules to regulate appetite-related hormone secretion and the immune system, or act directly on hypothalamic neurons. Herein, we summarize the effects of gut microbiota on host appetite and consider the potential molecular mechanisms. Furthermore, we propose that the manipulation of gut microbiota represents a clinical therapeutic potential for lessening the development and consequence of appetite-related disorders. Video abstract.

Dietary fiber and the microbiota: A narrative review by a group of experts from the Asociación Mexicana de Gastroenterología

Dietary fiber intake is one of the most influential and efficacious strategies for modulating the gut microbiota. Said fiber can be digested by the microbiota itself, producing numerous metabolites, which include the short-chain fatty acids (SCFAs). SCFAs have local and systemic functions that impact the composition and function of the gut microbiota, and consequently, human health. The aim of the present narrative review was to provide a document that serves as a frame of reference for a clear understanding of dietary fiber and its direct and indirect effects on health. The direct benefits of dietary fiber intake can be dependent on or independent of the gut microbiota. The use of dietary fiber by the gut microbiota involves several factors, including the fiber's physiochemical characteristics. Dietary fiber type influences the gut microbiota because not all bacterial species have the same capacity to produce the enzymes needed for its degradation. A low-fiber diet can affect the balance of the SCFAs produced. Dietary fiber indirectly benefits cardiometabolic health, digestive health, certain functional gastrointestinal disorders, and different diseases.

Gut Microbiota and Host Metabolism: From Proof of Concept to Therapeutic Intervention

The field of the gut microbiota is still a relatively young science area, yet many studies have already highlighted the translational potential of microbiome research in the context of human health and disease. However, like in many new fields, discoveries are occurring at a fast pace and have provided new hope for the development of novel clinical applications in many different medical conditions, not in the least in metabolic disorders. This rapid progress has left the field vulnerable to premature claims, misconceptions and criticism, both from within and outside the sector. Tackling these issues requires a broad collaborative effort within the research field and is only possible by acknowledging the difficulties and challenges that are faced and that are currently hindering clinical implementation. These issues include: the primarily descriptive nature of evidence, methodological concerns, disagreements in analysis techniques, lack of causality, and a rather limited molecular-based understanding of underlying mechanisms. In this review, we discuss various studies and models that helped identifying the microbiota as an attractive tool or target for developing various translational applications. We also discuss some of the limitations and try to clarify some common misconceptions that are still prevalent in the field.

Dietary fiber and the microbiota: A narrative review by a group of experts from the Asociación Mexicana de Gastroenterología

Dietary fiber intake is one of the most influential and efficacious strategies for modulating the gut microbiota. Said fiber can be digested by the microbiota itself, producing numerous metabolites, which include the short-chain fatty acids (SCFAs). SCFAs have local and systemic functions that impact the composition and function of the gut microbiota, and consequently, human health. The aim of the present narrative review was to provide a document that serves as a frame of reference for a clear understanding of dietary fiber and its direct and indirect effects on health. The direct benefits of dietary fiber intake can be dependent on or independent of the gut microbiota. The use of dietary fiber by the gut microbiota involves several factors, including the fiber's physiochemical characteristics. Dietary fiber type influences the gut microbiota because not all bacterial species have the same capacity to produce the enzymes needed for its degradation. A low-fiber diet can affect the balance of the SCFAs produced. Dietary fiber indirectly benefits cardiometabolic health, digestive health, certain functional gastrointestinal disorders, and different diseases.

Gut microbiome variation modulates the effects of dietary fiber on host metabolism

BACKGROUND

There is general consensus that consumption of dietary fermentable fiber improves cardiometabolic health, in part by promoting mutualistic microbes and by increasing production of beneficial metabolites in the distal gut. However, human studies have reported variations in the observed benefits among individuals consuming the same fiber. Several factors likely contribute to this variation, including host genetic and gut microbial differences. We hypothesized that gut microbial metabolism of dietary fiber represents an important and differential factor that modulates how dietary fiber impacts the host.

RESULTS

We examined genetically identical gnotobiotic mice harboring two distinct complex gut microbial communities and exposed to four isocaloric diets, each containing different fibers: (i) cellulose, (ii) inulin, (iii) pectin, (iv) a mix of 5 fermentable fibers (assorted fiber). Gut microbiome analysis showed that each transplanted community preserved a core of common taxa across diets that differentiated it from the other community, but there were variations in richness and bacterial taxa abundance within each community among the different diet treatments. Host epigenetic, transcriptional, and metabolomic analyses revealed diet-directed differences between animals colonized with the two communities, including variation in amino acids and lipid pathways that were associated with divergent health outcomes.

CONCLUSION

This study demonstrates that interindividual variation in the gut microbiome is causally linked to differential effects of dietary fiber on host metabolic phenotypes and suggests that a one-fits-all fiber supplementation approach to promote health is unlikely to elicit consistent effects across individuals. Overall, the presented results underscore the importance of microbe-diet interactions on host metabolism and suggest that gut microbes modulate dietary fiber efficacy. Video abstract.

Comparative analysis of type 2 diabetes-associated gut microbiota between Han and Mongolian people

Due to the different rates of diabetes in different ethnic groups and the structural differences in intestinal microbiota, this study evaluated the changes in diabetes-related intestinal microbiota in two ethnic groups. Fifty-six stool samples were collected from subjects from the Han and Mongolian ethnic groups in China, including participants without diabetes (non-diabetic, ND) and with type 2 diabetes (T2D). The 16S rDNA gene V3 + V4 area was extracted from microbiota, amplified by PCR, and used to perform high-throughput sequencing and screen differential microbiota associated with ethnicity. The results showed that there were 44 T2D-related bacterial markers in the Han subjects, of which Flavonifractor, Alistipes, Prevotella, Oscillibacter, Clostridium XlVa, and Lachnospiracea_incertae_sedis were most closely related to diabetes. There were 20 T2D-related bacterial markers in the Mongolian subjects, of which Fastidiosipila and Barnesiella were most closely related to diabetes. The common markers of T2D bacteria in the two ethnic groups were Papillibacter and Bifidobacterium. There were 17 metabolic pathways with significant differences between the ND and T2D groups in the Han group, and 29 metabolic pathways in the Mongolian group. The glutamatergic metabolic pathway was the only common metabolic pathway in two ethnic groups. The composition and function of diabetes-related bacteria were significantly different among the different ethnic groups, which suggested that the influence of ethnic differences should be fully considered when studying the association between diabetes and bacteria. In addition, the common bacterial markers found in diabetic patients of different ethnic groups in this study can be used as potential targets to study the pathogenesis and treatment of diabetes.